From bc7780d494c85dbfce46bf0ad47d259de79dea5b Mon Sep 17 00:00:00 2001
From: hermes-explorigin <tim+hermes@thecookiejar.me>
Date: Sun, 16 Aug 2026 20:00:14 +0000
Subject: [PATCH] Fix 7-day forecast day labels shifted by UTC date parsing

---
 src/components/DailyForecast.svelte    |  5 +++--
 src/lib/dates.js                       | 13 +++++++++++++
 src/lib/stores/notifications.svelte.js |  3 ++-
 3 files changed, 18 insertions(+), 3 deletions(-)
 create mode 100644 src/lib/dates.js

diff --git a/src/components/DailyForecast.svelte b/src/components/DailyForecast.svelte
index 9b760b9..8a23a62 100644
--- a/src/components/DailyForecast.svelte
+++ b/src/components/DailyForecast.svelte
@@ -1,6 +1,7 @@
 <script>
   import { app } from '../lib/stores/app.svelte.js'
   import { getWeatherInfo } from '../lib/api/weather-codes.js'
+  import { parseLocalDate } from '../lib/dates.js'
 
   const data = $derived(app.forecastData)
   const daily = $derived(data?.daily)
@@ -10,14 +11,14 @@
   function formatDay(dateStr, index) {
     if (index === 0) return 'Today'
     if (index === 1) return 'Tomorrow'
-    const d = new Date(dateStr)
+    const d = parseLocalDate(dateStr)
     return d.toLocaleDateString('en-US', { weekday: 'short', month: 'short', day: 'numeric' })
   }
 
   function getDayName(dateStr, index) {
     if (index === 0) return 'Today'
     if (index === 1) return 'Tomorrow'
-    return new Date(dateStr).toLocaleDateString('en-US', { weekday: 'long' })
+    return parseLocalDate(dateStr).toLocaleDateString('en-US', { weekday: 'long' })
   }
 </script>
 
diff --git a/src/lib/dates.js b/src/lib/dates.js
new file mode 100644
index 0000000..9807004
--- /dev/null
+++ b/src/lib/dates.js
@@ -0,0 +1,13 @@
+/**
+ * Date helpers for Open-Meteo strings.
+ *
+ * Open-Meteo returns calendar dates like "2026-08-19" (in the location's
+ * timezone). `new Date("2026-08-19")` parses that as UTC midnight, so in U.S.
+ * Central (UTC-5) it renders as the PREVIOUS weekday, shifting every day
+ * label one day back. Build the Date from its parts instead so it is a local
+ * calendar date with no offset/timezone shift.
+ */
+export function parseLocalDate(dateStr) {
+  const [y, m, d] = String(dateStr).split('-').map(Number)
+  return new Date(y, (m || 1) - 1, d || 1)
+}
diff --git a/src/lib/stores/notifications.svelte.js b/src/lib/stores/notifications.svelte.js
index 984742f..aa13473 100644
--- a/src/lib/stores/notifications.svelte.js
+++ b/src/lib/stores/notifications.svelte.js
@@ -7,6 +7,7 @@
 import { isSevereWeather } from '../api/weather-codes.js'
 import { app } from './app.svelte.js'
 import { saveSettings } from '../storage/db.js'
+import { parseLocalDate } from '../dates.js'
 
 export class NotificationStore {
   /** @type {Array<{ id: string, type: string, severity: 'info'|'warning'|'danger', message: string, icon: string }>} */
@@ -66,7 +67,7 @@ export class NotificationStore {
     if (daily.time) {
       for (let i = 0; i < daily.time.length && i < 3; i++) {
         const day = daily.time[i]
-        const dateLabel = i === 0 ? 'Today' : i === 1 ? 'Tomorrow' : new Date(day).toLocaleDateString('en-US', { weekday: 'short' })
+        const dateLabel = i === 0 ? 'Today' : i === 1 ? 'Tomorrow' : parseLocalDate(day).toLocaleDateString('en-US', { weekday: 'short' })
 
         const precip = daily.precipitation_probability_max?.[i] || 0
         if (precip >= t.precip) {